An analysis of vitamin K status in Chinese healthy children aged 0-18 years

Background: Vitamin K (VK), an essential fat-soluble nutrient, exists in two primary forms, vitamin K1 (VK1), and vitamin K2 (VK2). VK1 plays an essential role in blood coagulation, while VK2 plays a crucial role in managing bone calcification, supporting bone strength and health. However, comprehensive epidemiological data on VK remains sparse, particularly in children. This study aims to evaluate the levels and characteristics of VK in children of Wenzhou area, China.

Methods: A total of 3,342 children undergoing routine physical examinations in the outpatient department from December 2020 to August 2022 were recruited. The levels of VK (including VK1 and menaquinones (MK-4), a major form of VK2) and 25-hydroxy vitamin D (25(OH)D) in fasting serum samples from these children were measured using high-performance liquid chromatography-tandem mass spectrometry. The study analyzed the levels and distribution of VK and 25(OH)D across different sex, age, and weight groups, and explored their potential related factors.

Results: The median serum levels of MK-4 and VK1 were 0.12 (0.07, 0.21) ng/ml and 0.33 (0.18, 0.57) ng/ml, respectively. The reference ranges of MK-4 and VK1 were 0.01-0.58 ng/ml and 0.03-1.48 ng/ml, respectively. The median serum 25(OH)D level was 21.26 (17.30, 25.35) ng/ml. Moreover, there were no significant variations in the levels of MK-4 and VK1 across different age and sex groups. The level of MK-4 in the underweight group was significantly higher than that in the normal weight group. MK-4 level reached its peak in summer, while the VK1 concentration was at its lowest. Furthermore, a very weak positive correlation was revealed between MK-4 and VK1 levels.

Conclusion: In this study, we defined the median values and reference ranges of MK-4 and VK1 in a sample of Chinese children aged 0-18 years. MK-4 levels were higher in underweight children. Both MK-4 and VK1 levels exhibited seasonal variations. Further research is needed to explore the factors affecting MK-4 and VK1 levels.